Microsoft Corp. announced yesterday that it had appealed antitrust rulings by European regulators, hoping to overturn a fine of more than $600 million and directives to change its Windows software.

The appeal was filed with the European Court of First Instance, launching a process that could take several years. The company said it would also seek to have the orders put on hold pending the outcome of its appeals.

Although the fine is the largest ever levied in an antitrust case, it is the mandate to change the design of its software that the company is fighting the hardest. In March, the European Commission said Microsoft must produce two versions of its dominant Windows operating system, one without programs that play digital audio and video.

The regulators concluded that Microsoft was using its Windows dominance to elbow aside other makers of media-playing software that are not assured of the same ubiquitous distribution enjoyed by the Windows Media Player.

By requiring a version of Windows to be produced without its media player, the ruling ensures that computer makers that bundle operating systems into their machines could choose which media player to distribute.

Microsoft argued that the restrictions would effectively prevent it from adding new features to Windows.

"The Commission's decision undermines the innovative efforts of successful companies, imposing significant new obligations on successful companies to license their proprietary technology to competitors, and restrict companies' ability to add innovative improvements to their products," associate general counsel Horacio Gutierrez said in a prepared statement.

The court will likely hold a hearing in July or September on whether to put the sanctions on hold while the appeal proceeds.